What are the top five most powerful Senate committees?

Appropriations is the most powerful, having jurisdiction over most federal spending. After that in no particular order: Finance (jurisdiction over nearly all revenue, bonded debt, Medicare, Medicaid, and Social Security), Armed Services (broad military powers), Judiciary (jurisdiction over administrative law, and holds confirmation hearings for all federal judicial nominees). After that, probably Foreign Relations, followed by whatever committees have jurisdiction over whatever are hot-button issues at that time.